1. Field of the Invention
The present invention relates to a crystallized glass and a method for manufacturing the same, and more specifically, to a crystallized glass with the maximum negative coefficient of thermal expansion and a method for manufacturing the same, in which the crystallized glass has large crystals while its residual hyaline is minimized by selecting an optimum sintering temperature, and the like, according to weight ratios of raw materials used in glass manufacture, and solid-state reaction.
2. Description of Related Art
In general, a crystallized glass is a complex of crystals and glass, and generally obtained through a heat treatment after melting and molding raw materials used in glass manufacture.
The crystallized glass has often various properties that cannot be obtained from glass, and especially has an excellent thermal resistant thereby exhibiting low coefficient of thermal expansion. Therefore, it can be used for cooking utensils, a cuisson's top plate, a heater panel, and the like, and also used for a reflector of a telescope, raw materials for precision apparatus components, a wavelength filter, a coupler, or a waveguide of optical communication, and the like due to its good processability.
Especially, for the field of electronic materials, it is being well applied as a thermal expansion compensation material according to temperature changes of sealing, all kinds of substrates, and compositions so that recently there have been many experiments about a crystallized glass with negative coefficient of thermal expansion.
U.S. Pat. No. 4,209,229 discloses a crystallized glass, which has is β-eucryptite and β-quartz solid solution as a main crystal phase. However, the above crystallized glass has problems, such as very high crystallization temperature and about −2×10−7/° C. of negative coefficient of thermal expansion that is not sufficient.
U.S. Pat. No. 4,507,392 discloses a transparent crystallized glass containing β-quartz solid solution, which is suitable for decoration glaze of ceramics, as a main crystal phase. However, the crystallized glass has a great volume of nucleating agent so that it is difficult to get high negative coefficient of thermal expansion.
JP-A-2-208256 Laying-Open Gazette discloses ZnO—Al2O3—SiO2-based low thermal expansion ceramic that has β-quartz solid solution and/or Zn petalite solid solution as a main crystal phase. However, the above ceramic has a problem, such as −21.5×10−7/° C. of the lowest coefficient of thermal expansion that is not sufficient.
Furthermore, a method for manufacturing all of the above mentioned crystallized glasses includes precipitating crystals by re-heating a parent glass after manufacturing the parent glass by melting raw materials used in glass manufacture at high temperature. However, when a step of vitrification is performed at high temperature as mentioned above, it is a limitation on mass-production due to a considerable time and onerousness need for performing the method at high temperature.